Factors associating with the spread of RSV in infants

• Project/Area Number: 19K24250
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0908:Society medicine, nursing, and related fields
• Research Institution: Nagasaki University (2021); Tohoku University (2019-2020)
• Principal Investigator: OTOMARU Hirono 長崎大学, 熱帯医学研究所, 助教 (00849416)
• Project Period (FY): 2019-08-30 – 2022-03-31
• Project Status: Completed (Fiscal Year 2021)
• Budget Amount: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000); Fiscal Year 2020: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000); Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
• Keywords: RSV / 世帯内感染 / 感染伝播

Outline of Research at the Start

RSウイルスは特に6か月未満児に重症下気道感染症を引き起こすウイルスである。本研究では、乳児の感染源と感染拡大メカニズムの解明により、ワクチン効果を最大化させる接種対象の選定について検討する。方法として感染症モデルや分子疫学的解析を用いる。ワクチン接種の具体案の提案が可能となることが期待され、さらにワクチン導入後の効果の評価に応用できる可能性もある。

Outline of Final Research Achievements

Respiratory Syncytial Virus (RSV) is the causative virus of respiratory infections, particularly severe in infants. Although the importance of intra-household transmission has been reported, the detailed transmission dynamics remain unclear. This study aimed to examine the factors that associate with the spread of RSV to infants.
Based on the analysis of data collected in households in the Philippines in which a family member was infected with RSV, we showed that secondary infection occurred within a short period after the family member became infected. The risk of secondary infections in the household was significantly higher for children under five. Still, there was no association between this risk and the onset of cough in the index case.

Academic Significance and Societal Importance of the Research Achievements

RSVは世界的に流行が見られる下気道感染症の原因ウイルスである。本研究では、RSVの感染伝播に関連する疫学的な解析により、乳児を含む5歳未満児で特に二次感染率が高いことを示した。感染時点およびウイルス排出量の変化を推定する解析の結果、家族が最初に感染したのちのごく早い時期から二次感染が起きることが明らかになった。これらのことから、家族が感染した場合は速やかに感染予防策を実施する必要があることがわかった。また、症状が明らかではない感染者からも感染伝播が起きることから、症状に関わらないデータ収集の必要性が示された。大規模なRSV感染拡大を予防する対策の導入に必要となる知見を得ることができた。

Research Products

• [Int'l Joint Research] National University of Singapore/Saw Swee Hock School of Public Health(シンガポール)
• [Int'l Joint Research] Research Institute for Tropical Medicine(フィリピン)
• [Int'l Joint Research] Research Institute for Tropical Medicine(フィリピン)
• [Int'l Joint Research] National University of Singapore(シンガポール)
• [Int'l Joint Research] Research Institute for Tropical Medicine(フィリピン)
• [Journal Article] Risk of Transmission and Viral Shedding From the Time of Infection for Respiratory Syncytial Virus in Households (2021)
  • Author(s): Hirono Otomaru, Johanna Beulah T Sornillo, Taro Kamigaki, Samantha Louise P Bado, Michiko Okamoto, Mariko Saito-Obata, Marianette T Inobaya, Edelwisa Segubre-Mercado, Portia P Alday, Mayuko Saito, Veronica L Tallo, Beatriz P Quiambao, Hitoshi Oshitani, Alex R Cook
  • Journal Title: American Journal of Epidemiology Volume: 190 Issue: 12 Pages: 2536-2543
  • DOI: 10.1093/aje/kwab181
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] The change in pediatric hospitalization for acute respiratory infections associated with RSV in COVID-19 era in Vietnam (2021)
  • Author(s): Hirono Otomaru, Hien Anh Thi Nguyen, Michiko Toizumi, Duc Anh Dang, and Lay-Myint Yoshida
  • Organizer: An ISIRV-WHO Virtual Conference
  • Int'l Joint Research
• [Presentation] Epidemiological characteristic of social contact structure in Biliran Island, Philippines (2019)
  • Author(s): Hirono Otomaru, Johanna Beulah Tria Sornillo, Taro Kamigaki, and Hitoshi Oshitani
  • Organizer: Epidemics
  • Int'l Joint Research